1. Field of the Invention
This invention relates to a chemical-mechanical polishing (CMP) apparatus and method for highly accurately polishing a substrate such as a wafer, which is a workpiece.
2. Related Background Art
In recent years, the super minuteness and higher level difference of semiconductor devices have been advanced and along therewith, it has been required to highly accurately flatten the surfaces of substrates such as semiconductor wafers formed of Si, GaAs, InP or the like, and chemical-mechanical polishing apparatuses which will be described below are known as working means for flattening the surfaces of the substrates such as wafers highly accurately.
(1) As shown in FIG. 6 of the accompanying drawings, a chemical-mechanical polishing apparatus is provided with a workpiece rotating table 103 capable of removably holding a substrate 104 such as a semiconductor wafer formed of Si, GaAs, InP or the like on a lower surface shown in the figure, a polishing tool rotating table 101 integrally provided with a polishing pad 102 of a very large diameter as compared with the diameter of the substrate 104 disposed in opposed relationship with the underside of the workpiece rotating table 103, and a supply nozzle 106 for supplying an abrasive material (polishing slurry) 107 to the upper surface of the polishing pad 102, and is designed such that working pressure in the axial direction indicated by the white arrow is imparted to the rotary shaft 105 of the workpiece rotating table 103 holding the substrate 104 while the abrasing material (polishing slurry) 107 is supplied to the upper surface of the polishing pad 102 integrally provided on the polishing tool rotating table 101 rotated in the direction of arrow A, to thereby impart rotational motion indicated by arrow B and pivotal motion indicated by arrow C to the workpiece rotating table 103 holding the substrate 104 with the substrate 104 urged against the polishing pad 102, thus polishing the substrate.
(2) Shown in FIG. 7 of the accompanying drawing, is a chemical-mechanical polishing apparatus in which first to third polishing tool rotating tables 201a-201c of a very large diameter are juxtaposed on a base 205 and substrates (not shown) such as wafers held on first to third workpiece rotating tables 204a-204c disposed on a head 203 are polished at one time while being caused to bear against polishing pads 202a-202c integrally provided on the upper surfaces of the first to third polishing tool rotating tables 201a-201c, respectively, or the first to third polishing pads 202a-202c are made to differ in hardness or surface roughness and a substrate W is roughly polished and finish-polished by the first to third polishing pads 202a-202c and the polished chips are removed.
However, the above-described prior art suffers from the following problems still left to be solved.
(1) Since the diameter of the polishing tool rotating tables integrally provided with the polishing pads is very large as compared with the diameter of the substrate, the entire polishing apparatus including the polishing tool rotating tables becomes bulky, and when the polishing tool rotating tables are rotated at a high speed, vibrations are created and it becomes impossible to highly accurately polish the surface to be polished of the substrate which is a workpiece and therefore, the polishing tool rotating tables cannot be rotated at a high speed. As a result, the polishing speed (the amount of removal per unit time) cannot be made high.
(2) During polishing, foreign substances such as polishing chips cannot be removed and therefore, stable chemical-mechanical polishing cannot be done for a long time. Also, it is difficult to detect the surface shape of the surface to be polished of the substrate which is a workpiece in real time by a detecting device.